ATHENS/CHIOS, Greece (Reuters) - Refugees and migrants stuck in Greek camps, including children as young as nine, are cutting themselves, attempting suicide and using drugs to cope with the "endless misery", international charities said on Thursday.

In reports marking one year since the European Union struck a deal with Turkey to stem the flow of refugees and migrants to Greece, Save the Children and Medecins Sans Frontieres (MSF) found anxiety, depression and aggression were on the rise.

Mental health was "rapidly deteriorating due to the conditions created as a result of this deal", Save the Children said.

"One of the most shocking and appalling developments Save the Children staff have witnessed is the increase in suicide attempts and self-harm amongst children as young as nine," it said.

"Save the Children staff have seen children ... turn to substance abuse as a way of coping with the seemingly endless misery they face," it said.

The EU-Ankara deal came into force on March 20, 2016 after a million refugees and migrants from Syria, Iraq, Afghanistan and beyond reached Europe in 2015, crossing over to Greek islands from Turkey.

Under the deal, anyone who crosses into Greece without documents can be deported to Turkey unless they qualify for asylum in Greece. But long asylum procedures and a huge backlog have stranded 14,000 asylum seekers on five Greek islands, double the capacity.

The EU has hailed the deal as a success for stemming the tide of refugees and migrants to Europe through Greece.

The problems arising from the logjam do not just apply to children.

Save the Children described conditions in overcrowded camps as "degrading", forcing asylum-seekers to fight for basics such as blankets, a dry place to sleep, food and warm water.

"The living conditions have made them lose hope and made them feel like animals and objects," it quoted a staff member of Praksis, its partner organisation, as saying.

On the island of Lesbos, where more than 3,000 asylum-seekers live, MSF recorded a 2.5-fold increase in the percentage of patients with symptoms of anxiety and depression. Symptoms of psychosis and cases of self-harm and suicide also rose.

On nearby Samos, it found an escalation in suicide attempts in recent months based on 300 mental health consultations.

"They are losing any hope that they will find a safer, better future than the one they fled," said Jayne Grimes, an MSF psychologist on Samos.

In a bleak seaside tent camp on Chios island, hundreds more asylum-seekers wait for months with no clarity on their future.

"Why I cannot leave? How long more I must wait?" asked Jafar, an 18-year-old from Pakistan who arrived in Greece a year ago, on his way to the doctor to treat a cold.

"The conditions are turning children from young people who are calm and full of dreams to people who want to harm property, others and themselves," another Praksis member said.